Eretis umbra maculifera Mabille & Boullet 1916

COCK, MATTHEW J. W. & CONGDON, T. COLIN E., 2011, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera) principally from Kenya. Part 3. Pyrginae: Celaenorrhinini, Zootaxa 3033 (1), pp. 1-67 : 36-38

Eretis umbra maculifera Mabille & Boullet 1916 ( Figures 35–38 )

In his catalogue of the African Hesperiidae, Evans (1937) treated maculifera as one of four subspecies of Eretis djaelaelae . Subsequently ( Evans 1951), he transferred this subspecies, together with subspecies nox Neave from Zambia (NE Rhodesia), to be subspecies of E. umbra ( Trimen 1862) , the nominate subspecies of which is restricted to southern Africa. In his 1937 key, Evans characterised E. djaelaelae as having the male foreleg white, whereas in E. umbra it is brown, and this character is still used in South Africa ( Pringle et al. 1994; Henning et al. 1997). However, some confusion may have arisen because although some species have the male foreleg brilliant white, further emphasised by a well developed fringe ( E. lugens , E. djaelaelae ), others have it dull white ( E. umbra maculifera ). Furthermore, it can be seen that, at least in fresh specimens, the foreleg of the female may also be dull white ( Figure 35.2 ).

This is a species of dry open woodland. The caterpillar which I found, for example, was taken in the middle of an extensive grassy clearing amongst open woodland near Cottar's Camp on the edge of Masai Mara.

Adult behaviour

This species frequently rests on stones or on the ground, leaving to indulge in fast erratic, and difficult to follow flights. I have caught a female on top of a small hill beside the Magadi Road ( Cock & Congdon 2011, Figure Food plants

Van Someren (1974, as E. djaelaelae ) and Kielland (1990) give Asystasia mysorensis (= schimperi) ( Acanthaceae ) as the food plant. Dickson & Kroon (1978) give Dianthera trisulcata (= Chaetacanthus setiger ) as the food plant of ssp. umbra in southern Africa. Larsen (1991) lists Phaulopsis , Dyschoriste , Dianthera (= Chaetacanthus auct.), Justicia and Asystasia from the literature, but as he suggests, most of these records probably refer to E. djaelaelae based on the reports by Murray (1959) and Dickson & Kroon (1978). On the other hand, Henning et al. (1997) and Heath et al. (2002) give the same genera as Larsen (1991) for E. umbra umbra , but this could have been based on Larsen’s records. Further rearing or association of rearing records with voucher material will be needed to clarify the situation.

The only caterpillar of this species which I have found was on a low-growing, slightly succulent Acanthaceae near Cottar's Camp (Masai Mara). Unfortunately the food plant was not flowering, and although I transplanted it to my Nairobi garden where it survived for 18 months until I left Kenya, it never did flower. I showed a photograph of the vegetative plant ( Figure 36 ) to Iain Darbyshire and Kaj Vollesen of Kew Herbarium, who considered it to be probably Dyschoriste radicans .

Ovum The remains of the egg shell were found on the terminal leaf of the plant on which the caterpillar was collected.

Leaf shelters

The n–2 instar caterpillar was in a shelter made by rolling the edge of the leaf upwards; the lid portion was drying out and turning brown. I first spotted the shelter through the view-finder of my camera as I tried to photograph Caterpillar

The n–2 instar caterpillar measured 4 mm when collected, and was dark purple-grey with a dark head (0.76 x 0.83 mm wide x high). The penultimate instar caterpillar was similar but with a black head (1.14 x 1.21 mm wide x high); the instar lasted ten days. Both this and the previous instar caterpillar fed from the leaf upper surface without perforating the lamina.

The final instar caterpillar grew to about 12 mm ( Figure 37.1 ), and was very similar to that of Eretis lugens (Rogenhofer) . Head mat black; rugose; covered with scattered pale scales, stalked with a palmate distal area held parallel to the head surface; 2.4 x 2.6 mm wide x high ( Figure 37.2 ). Body dark grey-black; covered with scattered light dots, which under magnification can be seen to be very short, pale, stalked, stellate setae; dorsal line slightly darker; diffuse light yellowish spot dorsolaterally on anterior margin of A2–A8. Spiracles pale, but very small, inconspicuous. The final instar lasted 27 days under Nairobi conditions.

Pupa

Although the caterpillars of E. umbra maculifera and E. lugens are so similar, the pupae are very different. The three day old pupa shown in Figure 38 is dark, covered with a light waxy bloom, except for the mat black T1 spiracle and the dark vertical bar through the eye; erect pale setae except on appendages; proboscis extends to cremaster. In contrast the pupa of E. lugens discussed below is green with a black marking on the head, and only turns dark a day or two before the adult emerges. The pupa reared under Nairobi conditions took 15 days to develop.

Natural enemies

Dickson & Kroon (1978) record an Apanteles sp. from the final instar caterpillar of either E. djaelaelae djaelaelae or E. umbra .

Figures

FIGURE 35. Reared adult female Eretis umbra maculifera collected as n–2 caterpillar on Acanthaceae, probably Dyschoriste radicans (Figure 36), Cottar’s Camp, Masai Mara, 19 Feb 1990; emerged and photographed 18 Apr 1990; 90/21. 1, upper side. 2, under side showing dull white prolegs, palpi and antenna beneath.

FIGURE 36. Food plant of Eretis umbra maculifera, probably Dyschoriste radicans, Masai Mara (transplanted to Nairobi).

FIGURE 37. Final instar caterpillar of Eretis umbra maculifera. 1, collected as n–2 caterpillar on Acanthaceae (probably Dyschoriste radicans, Figure 36), Cottar’s Camp, Masai Mara, 19 Feb 1990; moulted to final instar 7 Mar; photographed 25 Mar 1990, 12 mm; pupated 3 Apr, 90/21. 2, as (1) but photographed 12 Mar 1990.

FIGURE 38. Pupa of Eretis umbra maculifera collected as n–2 caterpillar on Acanthaceae (probably Dyschoriste radicans, Figure 36), Cottar’s Camp, Masai Mara, 19 Feb 1990; pupated 3 Apr; photographed 6 Apr, 12 mm; emerged 18 Apr, 90/21. 1, lateral view. 2, ventrolateral view.